A Vanishing

With the first step the fading starts...
A warning first:
This slight eclipse
evades the senses and can never be
identified with time:
You'll never say
"I saw it start, it was at four-fifteen
and there was sunlight on the wall. We were awake
and drinking tea."

It happens out of sight,
just left or right of mind's imagining.

The second step becomes more obvious:
there's a distinct impression that some
parts are mixed with air,
and air's invisibility...
it's just a feeling, and that's really all
you can solidly identify.

With the third step it's done,
and having vanished
utterly
how should you tell yourself
what happened,
when?

It happens out of sight,
just left or right of mind's imagining